In recent years, wireless local area networks (LAN) represented by Institute of Electrical and Electronics Engineers (IEEE) 802.11 have become widespread. In wireless LANs, however, phenomena which interrupt communication may occur. The phenomena include, for example, propagation loss, shadowing, fading or collision of frames (packets) being transmitted, and the like. Due to the phenomena, assured reliability in communication on wireless LANs is desired for the purpose of wider distribution of wireless LANs.
Thus, standards of wireless LANs provide mechanisms for conveying successful reception of a frame to a transmission source of the frame. Specifically, a wireless communication device which has received a frame destined for the device transmits an acknowledgement (which will also be referred to as ACK below) frame. In a case in which the ACK frame is successfully received, a wireless communication device serving as a transmission source ends the transmission process of the frame, assuming that the transmission is completed. Conversely, in a case in which the ACK frame is not successfully received, the wireless communication device performs a re-transmission process of the frame, assuming that the transmission has failed.
Meanwhile, the number of wireless communication devices is increasing as well in accordance with the distribution of wireless LANs. If the number of wireless communication devices increases, there is a high possibility of communication efficiency deteriorating, and thus improvement of communication efficiency is desired.
With regard to the above-mentioned problem, technologies for performing efficient communication with a plurality of wireless communication devices have developed. As such a technology, for example, there is a multicast scheme in which a frame is transmitted to one or a plurality of wireless communication devices at a time. Note that a system in which a frame is transmitted to a single wireless communication device is called a unicast scheme.
Here, there are cases in which it is desired to apply the acknowledgement mechanism also to multicast frames in view of improvement of reliability in communication. Thus, the acknowledgement mechanism for multicast communication is provided in the standards of wireless LANs. Specifically, a wireless communication device that has transmitted a multicast frame transmits a block ACK request (which will also be referred to as block ACK request (BAR) below) frame to each of wireless communication devices serving as destinations of the multicast frame individually and receives a block ACK (which will also be referred to as block ACK (BA) below) frame as a response to the BAR frame. In addition, the wireless communication devices that have received the multicast frame destined for the devices transmit BA frames upon receiving the BAR frame in the unicast scheme.
For example, Patent Literature 1 discloses an invention related to a wireless communication device which exchanges a BAR frame and a BA frame with each of a plurality of terminals serving as destinations of multicast frames after the multicast frames destined for the plurality of terminals are transmitted.